The present invention relates to a material for preventing marine organisms deposition on marine arrangements such as ships, marine structures and marine facilities, and a production process for the same.
Deposition of marine organisms such as barnacles on marine arrangements including ships provides such troubles in terms of navigation as a reduction in the velocity due to an increase in the frictional resistance and brings about such various problems that it is unfavorable in terms of good appearance as well as functional problems that marine arrangements such as ships are corroded.
In these cases, taken is a measure to apply paint called antifouling paint to inhibit marine organisms deposition.
A mechanism of inhibiting marine organisms deposition by the above antifouling paint depends on dissolution of harmful metal. For example, a metal dissolution amount required for inhibiting barnacles deposition is 2 xcexcg per one square cm a day in the case of tin compounds and 16 xcexcg in the case of copper compounds.
As described above, antifouling paints blended with effective tin compounds have too strong toxicity and therefore the production thereof has been discontinued in 1997 in our country. Paints blended with copper compounds having toxicity, which is not so serious as those of tin compounds, are produced even at present and cause marine pollution.
In overseas countries such as France, Great Britain and U.S.A. other than our country, they are controlled in use because of too strong toxicity thereof. Paints of copper compounds which are alternate products thereof are used but have unsatisfactory effects, and therefore the existing state is that tin compounds-blended products having a strong toxicity are used as well to bring about serious marine pollution.
Worked out is a technique in which high corrosion resistant metal comprising titanium, zirconium, tantalum, niobium and alloy containing these metals as principal components is used without using the above antifouling paints to inhibit marine organisms deposition (Japanese Patent Application Laid-Open No. 109208/1995). However, depositing amounts of marine organisms are changed to a large extent due to a seasonal factor that barnacles of marine organisms are liable to deposit from early summer through autumn excluding some cold current species thereof, a regional factor of whether or not parrot fishes and black porgies which take barnacles for feeds are present and a factor of whether or not organic and inorganic nutrients are rich, which is a condition liable to cause the formation of a biological membrane by marine microorganisms which is said to be closely related to the deposition of marine organisms. Further, in marine organisms such as barnacles, larvae of barnacles are liable to deposit on ships which are operated at a lower frequency or parts which have less friction with sea water during running. Under the preceding conditions which are preferable for the deposition of marine organisms, the above technique disclosed in Japanese Patent Application Laid-Open No. 109208/1995 is not sufficiently effective and firm, and has had the defect that the deposition, which is not serious, of marine organisms is caused.
Further, techniques making use of silver having excellent antibacterial and bactericidal effects are disclosed in Japanese Patent Application Laid-Open No. 124327/1981, Japanese Patent Application Laid-Open No. 167798/1983, Japanese Patent Application Laid-Open No. 137629/1988 and Japanese Patent Application Laid-Open No. 120237/1989.
However, these patent techniques are techniques in which silver powder is blended into synthetic resin materials, aluminum porous anodic oxide membranes or rubber substrates to inhibit marine organisms deposition by the action of silver ions dissolved from this silver powder, and therefore there has been the problem that considering the strength and the cost of the materials, not only the mixing amount of the silver powder is restricted but also almost all silver powder is buried into the insides thereof to make it impossible to expect the sufficient effects.
Further, the base materials are synthetic resin materials and rubber substrates having low surface hardnesses, and therefore they have been restricted in use for marine arrangements such as ships to which particularly an abrasion resistance is required.
In using antifouling paints for preventing marine organisms deposition, there has been the problem that harmful metal ions are dissolved in the ocean to exert an adverse effect on the global environment.
Further, in using only high corrosion resistant metal comprising titanium, zirconium, tantalum, niobium and alloy containing these metals as principal components, it has been restricted in use under such severe condition as described above.
Furthermore, the techniques making use of silver powder having excellent antibacterial and bactericidal effects have involved, as described above, the problems that the blending amount is restricted and that almost all silver powder is buried and the defect that they can not be used for uses in which an abrasion resistance is required.
In light of the existing state described above, the present inventors shall provide a material which not only has no possibility to contaminate the ocean and is excellent in terms of good appearance but also is excellent in an abrasion resistance and can stably inhibit marine organisms deposition over a long period of time, and a production process for the same.
The present inventors experimented high corrosion resistant metal comprising titanium, zirconium, tantalum, niobium or alloy containing these metals as principal components which was developed previously under a condition in which marine organisms such as barnacles were liable to deposit to find that the deposition of marine organisms was caused.